diff options
| -rw-r--r-- | src/libstd/io/extensions.rs | 42 |
1 files changed, 14 insertions, 28 deletions
diff --git a/src/libstd/io/extensions.rs b/src/libstd/io/extensions.rs index f6e87212d17..548dc3efe92 100644 --- a/src/libstd/io/extensions.rs +++ b/src/libstd/io/extensions.rs @@ -51,23 +51,16 @@ impl<'r, R: Reader> Iterator<u8> for Bytes<'r, R> { } pub fn u64_to_le_bytes<T>(n: u64, size: uint, f: |v: &[u8]| -> T) -> T { + use unstable::intrinsics::{to_le16, to_le32, to_le64}; + use cast::transmute; + + // LLVM fails to properly optimize this when using shifts instead of the to_le* intrinsics assert!(size <= 8u); match size { 1u => f(&[n as u8]), - 2u => f(&[n as u8, - (n >> 8) as u8]), - 4u => f(&[n as u8, - (n >> 8) as u8, - (n >> 16) as u8, - (n >> 24) as u8]), - 8u => f(&[n as u8, - (n >> 8) as u8, - (n >> 16) as u8, - (n >> 24) as u8, - (n >> 32) as u8, - (n >> 40) as u8, - (n >> 48) as u8, - (n >> 56) as u8]), + 2u => f(unsafe { transmute::<i16, [u8, ..2]>(to_le16(n as i16)) }), + 4u => f(unsafe { transmute::<i32, [u8, ..4]>(to_le32(n as i32)) }), + 8u => f(unsafe { transmute::<i64, [u8, ..8]>(to_le64(n as i64)) }), _ => { let mut bytes: ~[u8] = ~[]; @@ -84,23 +77,16 @@ pub fn u64_to_le_bytes<T>(n: u64, size: uint, f: |v: &[u8]| -> T) -> T { } pub fn u64_to_be_bytes<T>(n: u64, size: uint, f: |v: &[u8]| -> T) -> T { + use unstable::intrinsics::{to_be16, to_be32, to_be64}; + use cast::transmute; + + // LLVM fails to properly optimize this when using shifts instead of the to_be* intrinsics assert!(size <= 8u); match size { 1u => f(&[n as u8]), - 2u => f(&[(n >> 8) as u8, - n as u8]), - 4u => f(&[(n >> 24) as u8, - (n >> 16) as u8, - (n >> 8) as u8, - n as u8]), - 8u => f(&[(n >> 56) as u8, - (n >> 48) as u8, - (n >> 40) as u8, - (n >> 32) as u8, - (n >> 24) as u8, - (n >> 16) as u8, - (n >> 8) as u8, - n as u8]), + 2u => f(unsafe { transmute::<i16, [u8, ..2]>(to_be16(n as i16)) }), + 4u => f(unsafe { transmute::<i32, [u8, ..4]>(to_be32(n as i32)) }), + 8u => f(unsafe { transmute::<i64, [u8, ..8]>(to_be64(n as i64)) }), _ => { let mut bytes: ~[u8] = ~[]; let mut i = size; |